While today's line worker tends to rely on a hydraulic boom and bucket to reach electrical power lines or telephone poles, there are still instances where the line worker must manually climb a pole. This is the case where the pole cannot be reached by the boom truck, for example, a pole situated in the middle of a field in a rural setting. Having less practice, the worker is at increased risk of falling during such climbing.
To climb a pole, the line worker typically uses climbing spikes or spurs, and a climbing belt made from leather or suitable synthetic material. The climbing belt passes around the far side of the pole and attaches to a body-belt or harness which is worn by the line worker. The climbing spikes face inward to the pole and penetrate the pole giving the climber purchase for climbing. The climbing belt provides a climbing aid to the climber and also holds him to the pole and helps support his weight, freeing his hands.
While the climbing belt helps support the climber if used during ascent and descent (and also in the work position), problems occur if the climber loses his footing and begins to fall. In such a situation, or, if the worker has been standing upright on his spurs to be close to the pole and its equipment, and he then slips, the pressure of the climber's weight against the climbing belt may be relieved, so that the belt no longer pulls against the pole. This permits the climber to fall and be seriously injured or even killed. To arrest the climber during a fall, various fall arrest features have been incorporated into climber safety devices.
U.S. Pat. No. 4,407,391, which issued to Greenway et al., on Oct. 4, 1983 discloses a fall arrest device comprising a yoke with a safety belt attachment and handles for the climber. The yoke is formed from metal and closes around the pole. On the underside of the yoke, there are blades which can pivot and which, in their closed position, bite into the pole. Either counterweights on the blades, or torsion springs, hold them in the closed position. In operation, the climber holds the blades in the open position and lifts the yoke as he climbs the pole. Should the climber fall, he will normally release the blade handles and they will close either by the spring action or by the force of the counterweights, and will bite into the pole.
The device as taught by Greenway suffers a major drawback, namely, ease of use in the field. It will be appreciated that the usefulness of a fall arrest device depends on the line climber's willingness to use it. The Greenway device, besides being very heavy when compared to conventional safety belts, is very difficult to operate around obstructions on the pole (which are frequent). Furthermore, the yoke is not readily adjustable to different size poles. For these reasons, climbers have been quite reluctant to use this fall arrest device.
U.S. Pat. No. 4,579,196, which issued to Allen et al. on Apr. 1, 1986, discloses a climber fall arrest belt assembly having an outer strap and an inner strap. The outer strap includes downwardly directed teeth which are designed to bite into the pole. The outer strap wraps around the outside surface of the utility pole and connects to the climber's body-belt. The inner strap clips across the outer strap on the inner side of the pole but requires adjustment by the worker to fit the pole. In the event of a fall the teeth on the outer strap bite into the pole and the inner strap cooperates with the outer strap by bearing the climber's weight to stop the fall. The Allen invention suffers from the major drawback of having the fall arresting teeth always in the engaged position. Not only can the teeth catch during normal ascent and descent of the pole, but also the points on the teeth will tend to dull, thereby risking a failure in the event of the fall. In addition, the Allen invention uses friction between the inner strap and utility pole to bear some of the fallen climber's weight.
Accordingly, the problem remains to provide a fall arrest assembly which is reliable and easy to use by a line worker or other climber in the field. The prior art, while teaching various fall arrest devices, fails to provide a device which is not cumbersome and which does not interfere with the climber's normal ascent or descent of a utility pole. In addition, in the prior art, adjustment of the device to the changing diameters of poles is usually awkward.